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LHC (SSC) Byung Yunn CASA
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Parameters Type: Synchrotron Circumference: 26.659 (82.944) km
Proton energy: 7.7 (20) TeV Bunch length: 7.5 (6 to 7.5) cm Energy spread: 1.05e-4 (0.5e-4) Transverse emittance: 3.75 (1.0) µm Longitudinal emittance: 2.5 (0.233) eV-s
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continued Protons per bunch: 1.0e11 (7.3e9)
Average beam current: 850 (73) mA Number of bunches: 4725 (17100) RF frequency: (374.74) MHz RF voltage: 16 (20) MV Synchrotron tune: (0.0019) Momentum compaction: 2.94e-4 (2.23e-4)
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continued Nominal full crossing angle: 200 (75) µrad
Bunch spacing: 15 (16) ns Beta star: 50 (50) cm Beam-beam tune shift: ( ) Luminosity (/cm^2-s ): 1.65e34 (1.0e33) Number of interaction points: 3 (4) Synchrotron radiation power (per beam): 9.1 (9.1) kw
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Injectors (LHC) 50 MeV proton linac (180 mA for 7 µs), injected into 4 PS booster rings PS booster: accelerated in one bunch up to 1.4 GeV, PS accepts eight 200 ns long bunches 26 GeV PS (1/11 of SPS): debunched and rebunched at 26 GeV to 1.0e11 protons per bunch (emittance = 3 µm, bunch length = 9 ns) 450 GeV SPS (7/27 of LHC): 36 SPS beam pulses to fill one LHC channel.
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Injectors (SSC) 600 MeV H- linac: 125 m, RF Freq = 49.5 MHz (RFQ), 445 MHz (DTL), 1336 MHz (SCL) 8 GeV LEB: 250 m, RF Freq = MHz 100 GeV MEB: 1.9 km, RF Freq = 62.5 MHz 1 TeV HEB (Superconducting): 6 km, RF Freq = 62.5 MHz Average current (mA): 3.9 (Linac), 99 (LEB), 92 (MEB), 87 (HEB)
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Collider ring (LHC) Built on top (1.21 m) of LEP and has eightfold symmetry Two beam channels in the same magnet 10 Tesla dipole field (4 to 6 Tesla available) Can be used to collide ions Number of arcs: 8 Number of interaction regions: 8 (3 collision and 2 utility)
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Collider ring (SSC) Two rings separated vertically (0.7 m)
Dipole field: 6.6 T Quad in arcs: 212 T/m Interaction regions (IR) are arranged in 2 clusters (East and West) for cost effectiveness 4 IRs in each cluster and each IR is 2.4 km long Clusters are joined by arcs of 11.7 km radius
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Lattice (LHC) Two beam channels in the same plane (18 cm separation in arcs) and cross at eight points. Eight 25 FODO cells (98 m long and phase advance of 90 deg per cell) per ring Four 9 m long dipoles and one 3 m quad in a half cell Beta in arcs: max 166 m, min 29 m Dispersion in arcs: max 1.86 m, min 0.9 m
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continued Working point: (71.28, 70.31)
Insertion: 886 m long and phase advance in each plane by 2.5 units Chromaticity correction: sextupoles next to the main quads, powered in 2 families Linear aperture: 4 mm
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Lattice (SSC) FODO cell: 192 m long and phase advance of 60 deg
Five 16.5 m long dipoles and one 3.3m arc quad in each half cell Eight 42 cells per ring Beta in arcs: max 332 m, min 111 m Dispersion in arcs: max 3.92 m, min 2.36 m Natural chromaticity: -204
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continued Working point: (78.27, 78.28)
Chromaticity correction: sextupoles next to the main quads, powered in 2 families Linear aperture: 5 mm
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Collision IR (LHC) 40 m free space between final quad triplets
Beta star: can be tuned from 0.5 m to 15 m Beta max: 4 km Beam radius at IP: 15 µm Beam divergence at IP: 30 µrad
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Collision IR (SSC) 40 m free space between final quad triplets
Beta star: 0.5 m Beta max: 8 km Beam crossing angle at IR: 75 µrad, but can vary from 0 to 150 µrad
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Collective Effects (LHC)
Beam lifetime: 26.5 h Luminosity lifetime: 11 h IBS emittance growth time: 100 h (horizontal), 60 h (longitudinal) Longitudinal microwave and transverse mode coupling instability are potential dangers. Coupled bunch instabilities require active feedback systems to control.
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Collective Effects (SSC)
Beam lifetime: h Luminosity lifetime: 24 h IBS emittance growth time: 126 h (horizontal), 277 h (longitudinal) Relatively safe from single bunch instabilities. Coupled bunch instabilities require active feedback systems to control.
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